Air freight containers are used store and transport freight such as packages, perishable goods, mail and the like for loading onto cargo and passenger planes. Such containers are pre-loaded with cargo and subsequently loaded onto aircraft to reduce the time it takes to load the aircraft and to ensure that all available space in the aircraft is utilised. Air freight containers also protect the cargo from rain and snow during the aircraft loading process.
There is limited space available in aircraft and air freight containers are typically shaped to make the most of the available space. One of the most common type of air freight containers is in the shape of a cube with a trapezoidal extension at one end to generally conform to the shape of the curved side walls of an aircraft's cargo hold. Such air freight containers are also known as “unit load devices”. Such containers have been used by the airline industry for about thirty years.
One problem with the use of air freight containers is imbalance, which occurs when there are too many containers at one airport and not enough at another. To correct these imbalances, surplus empty containers have to be shipped to their desired location, which is wasteful and costly particularly when an entire aircraft is filled with empty containers for shipping from one continent to another.
A further problem is maintenance. Air freight containers are light, typically weighing about 80 Kg. Because they are lightly built, they are easily damaged and often have to be taken out of service for repair, typically at least twice a year.
There have been a small number of proposals for collapsible air freight containers. U.S. Pat. No. 5,941,405 proposes one such collapsible container. The proposed container has an aluminium base and top but collapsible fabric side walls. However it is likely that the collapsible container of U.S. Pat. No. 5,941,405 having fabric side walls would not be sufficiently strong for practical commercial use. U.S. Pat. No. 6,299,009 also discloses a proposed design of collapsible air freight container but which, when collapsed, is not particularly compact.
Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is solely for the purpose of providing a context for the present invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed before the priority date of each claim of this application.